VRT – my experiences as a grower

WMG Updates 2015Erin Cahill

“Insanity is doing the same thing over and over again and

expecting a different result”

Albert Einstein

OverviewBackground Steps to adoptionTools usedExamplesSummary

Summary

Our OperationOwn, Lease and Sharefarm 1450haFull cropping – Wheat,Barley,Canola,LupinsTwo locations 53 km apart – Highly variable

soils“Dalkey” (Walebing) - High production (High

inputs)• York gum loams,• White gum gravelly loams• Mallee gravels and cap-rock

“Elsewhere” (Rowes Rd) – Medium productionCasuarina gravelly duplex Pear tree yellow sandBlackbutt sands

VR – the journey so far

Yield mapping since 2007 (Case AFS)Auto steer 2007 ( JD Greenstar)Mapped all paddock boundaries 2007Prior to 2009 varying rates paddock to paddock

but not within (except K).2009 > map based variable rate post-em

nitrogen only2008 and 2009 collected PCD data for whole farm

VR – the journey so far

2009 – New Morris airseeder tank (Topcon controller)

2010 began map based VR at seeding -Issues with different systems talking to each other

-map prep clunky and time consumingBeginning 2012 converted airseeder to Greenstar 2012 EM 38/ radiometric survey part of farm2014 completed EM 38/ radiometric survey rest of

farm

Tools I use for VRSoil testing – all paddocks 0-30cm, some 0-50cm

& 0-1mPlant test – every yearHigh Res aerial photography or google -cheapYield maps – Minimum 3 yearsGuidance shapefiles- collect ASAPBiomass imagery (20m x 20 m) DMS imagery (Plant cell density 1m x 1m))EM 38/ Radiometrics

Tools I use for VRJD ApexSMS advanced (yield maps)VA GatewayGoogle EarthI Pad – ground truthingPenetrometerShovel !

Building Layers to manage Risk

VR processesTarget soil sampling sites

Identify and isolate main production limitations

Ground truth to understand drivers of variability – shallow soils, non wetting, weeds, root disease, vermin

Quantify production potential (go to yield maps)

Identify potential management zones

Keep application strategy simpleUse loss of GPS/out of field rate as my rate for

main zone

VR Nitrogen

Yield Maps Are a tool in the kit bag – nothing moreEasy and cheap to collect- start now1 year of yield mapping is inadequate for

VR 3 years of good quality yield maps as a

minimum is required to get a good picture of “true” spatial variability

are useless unless they are used to identify, understand and then manage the drivers of variability.

VR ProcessKeep simple- 3-4 zones per paddockKeep Zone boundaries practical for machineryMake rate changes worthwhile

- Min 20-25 kg/ha Compound (3-4 kg/ha P) - Min 25-30 l/h a Flexi N (10-13 kg/ha N)

Better matching of inputs to yield potentialWe are not using less fertiliser (just using it

better)

VR Nitogen – Manually Done

VR simple example

Weed mapping

Wild oats Spray all (80 ha & $2000)

Or patch spray (28 ha & $700)

Results2010 Average N saving $7-8/ha2012 Average N saving $15-16/haSignificant grain quality improvements (malt

barley)Yields achieved in the most productive parts of

paddocks have increasedNot wasting $ on poor/constrained areasCompound fert better allocation of $ (no real

saving)Identifing more areas to “fix”

SummaryPick your GPS/VR system and fit machinery

around it (one system throughout is best)Try not to be the guinea pig Collect good data even if you aren’t using it

nowUse documentation systemsLimit guess workBe clear about what you are varying and whyGround truth Don’t over commit in the early stages- time

hungry

SummaryVR applications need constant re-evaluation

– what was once a poor area may become a productive one if limitations are rectified

Use Check strips and analyse outcomesDon’t vary rates just for the sake of itRemember the goals are improved

productivity and profitability

Thankyou & Questions

Nutrient Budget approach to VRTWorks on the basis of replacing what is removedOnly works when we are in a situation where we

can maintenance fertilise!Makes no effort to understand drivers of spatial

variabilityMakes no allowance for losses due to soil reactions Makes no allowance for the fact that it takes more

nutrients to grow a crop than are removed eg to grow 1 t/ha wheat takes 50 kg N ha

1 t/ha wheat removes 20 kg N ha

Paddock variations drive savings

Paddock 1 71 haOutside lap 3.38 km 14% of paddock area (10.14 ha) with a 30m

swath11% of paddock area (8.11 ha) with a 24m swath

Paddock 2 69 haOutside lap 8.69 km37 %of paddock area (26 ha) with a 30m swath30% of paddock area (20.85 ha) with a 24m

swath

Paddock variations drive savings

Understand biggest limiting factor